Mitochondria are small structures inside most of our cells. They finish the work of breaking down sugars, using oxygen, and in doing so they make most of the cell’s ATP. Without them, an animal cell would depend on glycolysis alone, and completing the process in the mitochondria makes about fifteen times more ATP than glycolysis does (Alberts et al., 2002b).
The final step of that process runs through cytochrome c oxidase, the enzyme thought to absorb red and near-infrared light in photobiomodulation. Most of a cell’s oxygen use happens at this step (de Freitas & Hamblin, 2016).
Why it matters
When people say red light “works on the mitochondria,” this is what they mean. The absorption is well established. The full chain from absorption to benefit is still described by researchers as a hypothesis.
References
Alberts, B., Johnson, A., Lewis, J., Raff, M., Roberts, K., & Walter, P. (2002b). The mitochondrion. In Molecular biology of the cell (4th ed.). Garland Science. https://www.ncbi.nlm.nih.gov/books/NBK26894/
de Freitas, L. F., & Hamblin, M. R. (2016). Proposed mechanisms of photobiomodulation or low-level light therapy. IEEE Journal of Selected Topics in Quantum Electronics, 22(3), 348–364. https://doi.org/10.1109/JSTQE.2016.2561201